Dear Matthew,
You seem to have been unlucky with this data collection. STARANISO
would be prepared to see significant data extending to 2.0A along a*, 2.7A
along b*, and 1.7A along c*. The latter limit, however, involves some guess
work via the fitting by an ellipsoid of a cut-off surface that is very much
perturbed by the fact that you have a both a cusp and a truncation by the
detector edges in that direction. Without those, it looks quite probable
that you would have good solid data extending beyond 1.6A - if only you
could redo the experiment in such a way as to actually measure them ;-) .
As Eleanor said, it is a bad idea to make decisions about data on the
basis of the "downstream" criteria you were mentioning. STARANISO is not
just a numerical program that estimates numbers and suggests some sensible
actions that it will carry out for you: it is also a 3D visualisation tool
that shows you much more about your data and its possible shortcomings than
any Table1-style numbers ever will. If there are indeed deficiencies in the
data, like here, these 3D pictures will often point out what shortcomings in
your experiment are responsible for them. In that case, a new experiment, if
feasible, is always better than any surgery on the deficient data.
Please feel free to get in touch off-line if you would like more
details, such as patterns of outliers that we have observed.
With best wishes,
The STARANISO developers.
--
On Sun, Jun 21, 2020 at 05:33:53PM +0100, Eleanor Dodson wrote:
> *Please* dont throw good 1.8A data for the sake of statistics!
> You should see more detail along certain directions
> You will publish your structure providing honest details of the anisotropy
> (I hope..) but it is the map quality that matters ..
> Eleanor
>
> On Sun, 21 Jun 2020 at 15:16, Matthew Snee <
> [log in to unmask]> wrote:
>
> > Hi everyone.
> >
> > I have an x ray structure that I am finishing up, and there are a few
> > ambiguous regions where the peptide is poorly resolved.
> >
> > The data is highly anisotrophic, and requires truncation to around 2.4A to
> > achieve acceptable merging stats, although there is data in the "good"
> > direction going as high as 1.8-1.9A (determined by merging stats when using
> > elliptical cutoff).
> >
> > I have tried feeding my integration outputs to STARANISO with both the
> > elliptical and spherical cutoffs, but neither produce better results than
> > Xia2 Dials, as both need to be truncated further than 2.3A before they give
> > the same refinement stats (i.e it's best to just let refmac/phenix.refine
> > deal with the anistropy).
> >
> > As I understand it, anisotrophy can lead to loss of high resolution detail
> > because weak observations from the high res shells in the bad direction are
> > down-weighted, So any tricks to improve map quality (or conversely refining
> > data with poor completeness) would be appreciated.
> >
> > I'm not holding out hope that I can deposit anything better than 2.3A, but
> > Improving the maps might really help me with some of these troublesome
> > loops :)
> >
> > Cheers
> >
> > Matthew.
> >
> > Sent from Outlook Mobile <https://aka.ms/blhgte>
> >
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